Preparatory to welding a pair of metal plates and the like to one another it is necessary that the two plates be so positioned relatively to one another that a proper weld may be achieved. In preparing the two plates to be welded together, they usually are positioned adjacent one another with the edges to be welded confronting one another and spaced by a gap. It is rather uncommon for the confronting edges of the two members to match perfectly. On the contrary, more often than not the confronting edges are mismatched. That is, warpage, bending, or other distortion of the plates commonly will cause a surface of one member to be non-planar with the corresponding surface of the other plane. Further, it often is necessary to weld together two plates of different thicknesses and in such manner that corresponding surfaces at one side only of such plates are coplanar.
To correct non-planar conditions caused by warpage, deformation, or other distortion, it is common to use various kinds of shims, clamps, and the like which enable the confronting edges of a pair of plates to be adjusted relative to one another so that at least one surface of one plate is coplanar with the corresponding surface of the other plate. A tool for such purpose is illustrated in U.S. Pat. No. 4,175,734.
It is not uncommon that plates of different thicknessess are to be welded to one another. In such cases, it sometimes is desirable that corresponding surfaces of the plates be coplanar and the opposite corresponding surfaces of the plates be stepped. In other cases, however, it is desirable that both surfaces be stepped at the juncture of such plates. A tool adapted for use in the welding together of plates of different thicknesses is disclosed in U.S. Pat. No. 2,672,839.
Tools of the kind disclosed in the aforementioned patents have limitations in their effectiveness for a number of reasons, a principal one of which is that the tool parts that are adapted to span a gap between a pair of plates and be located on opposite sides of the plates are symmetrical on opposite sides of the gap, as a consequence of which forces applied to the plates on opposite sides of the gap are equal. In a construction in which the force applying member applies equal forces to two members on opposite sides of a gap, it is difficult, if not not impossible, to achieve the application of a greater effective force on one side of the gap than on the other once corresponding surfaces of the plates on opposite sides of the gap have been brought into coplanar relationship. Thus, it may not be possible to adjust the plates so that the corresponding surfaces on a selected side of such plates are planar or non-planar, or so that a thinner plate is stepped on both sides of its juncture with a thicker plate.
A tool constructed in accordance with the invention overcomes the disadvantages of the known tools by providing force applying means applicable to opposite sides of a pair of plates, each of the force applying members being capable of adjustments relative to the other so as to enable forces of different effective magnitude to be applied on opposite sides of a gap that is spanned by such members.